TS808 frustrating debug

[Sidahmed]

Hi everyone, yes this anooother ts808 debug, and yes I saw nearly all the topics about debugging a ts808 BUT here where I'm getting frustrated...First of all, let me tell you that I'm still a begginer in pedal building since I love DIY I wanted to start the journey I did a ts808 based on the TS808 TubeScreamer of Effectslayout: https://effectslayouts.blogspot.com/2015/02/ibanez-ts808-tube-screamer.html  , I did it on perfboard, I substituted some parts : 22nF for the 27nF input cap, put a 47pF instead of 51pF since I didn't have the right values, and I changed the 220nF on tone section into a 100nF to have some range on my tone pot. 

After all the wiring, I tested continuity, checked for shorts, I tested the effect and BAM it sounds really clean when I engage the pedal (using a toggle switch DPDT,  no 3pdt in my country), by clean I mean that even when i get the DRIVE pot all the way up i still have similar clean sound , when I play with TONE and LEVEL pots all the way up and down I have a reaaally subtle change in sound (but still clean).

My main problem is that even when i tested the effect voltages with multimeter (set on DC 20V) I had 0v every where, I put the Black wire on ground and test with the Red wire the effect...0V all time (Supply battery is 9.72V) 

I really need help if anyone can show me the path . Thanks a lot

[Kevin Mitchell]

Welcome to the magical world of DIY 

If you're getting 0v all around you wouldn't have any signal at the output when the effect is engaged. Likely a short, wiring issue and/or you're just not using your multimeter right 

Check your connections again
Verify the semiconductors you've chosen have the same pin orientation as the ones used in the referenced circuit.
Verify that pin 4 of the opamp and pin 3 of both transistors match your positive power line. If there is only 0 volts you will need to find where it's shorting out or where you've made a routing mistake.

[MrStab]

hi Sid!

does the volume pot kill the volume completely when turned? if not, could you describe the subtle difference it makes?
does your guitar seem to lose treble and sustain when the circuit is activated?

i think the signal would be totally absent or distort in a bad-sounding way if there was a power supply issue, so i wonder if maybe the signal is skipping some of the Tube Screamer stages via. a short-circuit, and somehow manages to reach the output without being affected much.

like Kevin says, make sure you're using the multimeter right. i still make mistakes and get confused after 5 years or so!

[Sidahmed]

Hi, thanks for the answers.
I got some precisions I forgot to mention, since i use a Dpdt ON-ON toggle switch, when I engage it up I have that clean sound, the tone knob is all the way up and i get a nearly not noticeable tone change, but when I got the toggle down no more sound at all (perhaps it worse than I thought haha, still a noob).

I checked my connections, resoldered some, checked with my continuity test every single point, and tried to see some microshorts but none.... still got no voltages when I use the DMM perhaps Im using it wrong idk. For the offboard wiring I used the 1st one of tonepad gor dpdt without led or DC, just for testing (I will attach some images to show you my Dmm setting and the offboard wiring)

Thanks

[antonis]

Plz allow me some kind of "nooby" guess.. 

You're checking for DC voltages and you get 0V everywhere (non-working circuit) WHILE you get clean sound through it, when effect engaged (working circuit, out of individual specs) AND no sound at all when effect by-passed..


Second coffee not finished yet (Stephen will slap my hand.. ) but it seems to me you didn't wire GND on Input jack sleeve while you're confused about DPDT switch status..
(meaning, when effect is actually ON you think it's OFF and vice versa..)

[MrStab]

FWIW i found perfboard very confusing until i began to memorise schematics. i found veroboard/stripboard to be easier when using other people's layouts, as there's just a bit less room for error (IMO).

i don't know why all these tutorials for beginners insist on including a footswitch and input-jack-power-switching. it's essential knowledge, but it causes a lot of confusion to lump it all together.

as you may know, the battery negative and the rest of Ground need to be connected for the circuit to work, and a mono guitar plug will connect the ring and the sleeve terminals. a stereo plug will not. make sure you have Tip, Ring and Sleeve in the correct order. one suggestion would be to just clip the battery negative from the input jack's ring, connect it to the sleeve (with all the other grounds), and test it like that.

i'm only 1 coffee in, so Antonis is probably making a lot more sense than me

[Sidahmed]

Ok guys, I got some news

I did another soldering of some points, rewired the jacks and the switch to the board and yeah the sleeve of the Output jack was lacking some solder when I solder it, it's on point now, the effect is working, I mean that the pedal responds very good to the knobs :p but, cuz there's always a but, It seems like the sound is a normal overdrive, it doesn't have that TS signature, idk perhaps it is just due to my little speaker in the amp haha, or perhaps the 100nF i changed in the tone section, well idk . Signal is ok, effect working, overdrive tone and level all working. I have some Hum when i engage the pedal is it normal?

I still have a question about voltages, since my effect is working and I have output, why am I still having those 0V in my DMM all the time ? I am sure I'm doing it wrong, I just followed the manual and it seems that it should work, DMM set on 20V (as shown in the image I attached before), The black wire on Ground and the Red wire on pins of IC or Trans. Need help for that.

Thanks for helping guys, it's cool

[ElectricDruid]

Your DMM setting looks fine; DC voltage, and up to 20V. Ideal for the job. The other potential foul-up is to put the probes in the wrong sockets on the DMM, or (more commonly) change to a different setting and forget to move them. I do that all the time switching over to measuring current from voltage. But your probes are in the right holes for voltage measurements, so that's all good.

Can you measure the voltage on a battery, or from your power supply if you're using one? If you've got a negative-centre pedal power supply, you can stick the black probe down the hole in the barrel and then touch the outside of the barrel with the red probe and you should see the 9V. If that doesn't work, either the DMM is broken or something really weird is going on! If that does work, then you've proved the meter is ok, and you can take a reading and you can plug the power into the circuit and start to try and follow it through. Where does it first go on the circuit board? Can you find a voltage there? Can you find a voltage on the IC?

All of this stuff seems easy once you've got the hang of it, but like anything it takes practice to do reliably.

HTH,
Tom

[Sidahmed]

I do read the voltage of my battery which is 9.54v now, that's why I don't understand why I can't read the voltages on my circuit, I connected the Black probe on Ground of the circuit and the Red probe on each of the 8 pins of the IC and hell i can't even get voltages on the DMM screen, too weird. I tried on many ground connections, i did it on the sleeve of the two jacks and the red probe on on IC pins or Trans E.B.C ...nothing, still 0.  If there is a technique or something to do the manipulation correctly (solder side or component side), let me know it

thanks

[bluebunny]

What voltage do you read at the point where the 9V enters your board (i.e. the "+9V" pad)?

[antonis]

Do you use a stereo Input jack (with sleeve and ring)..??

If yes, is Input plug plugged when you take measurements..??

[Sidahmed]

Bluebunny, i read 9.54 if i connect black and red probe to the battery, or one probe to the battery and the other probe in one point of the circuit, which is logical to read the same value IMO

Antonis, yes I have a stereo input jack, negative of battery on the ring, tip on the dpdt switch, and sleeve to ground. And no I don't measure it plugged, is it the problem? Lol

[patrick398]

Bluebunny, i read 9.54 if i connect black and red probe to the battery, or one probe to the battery and the other probe in one point of the circuit, which is logical to read the same value IMO

Antonis, yes I have a stereo input jack, negative of battery on the ring, tip on the dpdt switch, and sleeve to ground. And no I don't measure it plugged, is it the problem? Lol

I think that might be why you're reading 0v when the input jack is unplugged. The stereo input jack acts as a switch, when you unplug the guitar cable it breaks the connection between the ring and the sleeve meaning that the battery is essentiall 'turned off' because the negative lead no longer has a path to ground. It's a simple way of preserving battery life.

I assume you're running this on battery alone?

Try take readings with you DMM with the input cable plugged in, you should be seeing voltage now

[Sidahmed]

Okay thank you buddy, I'll test it as soon as I come back from work.  I will post the voltages if it works and if possible you tell if it is correctly working.

[patrick398]

Yes post IC voltages and maybe transistor and diode voltages if applicable. You say it's working but there is hum? Sounds like there could be a missing ground connection somewhere. Set your multimeter on 'Continuity' setting and with the input cable plugged in touch one lead to the sleeve of your input jack and the other lead to all the points in the circuit that should be ground. There should be continuity between all of them.
Hum could be coming from somewhere else but that's the first thing i'd check.

[EBK]

Could you post some pics of your board?

[ElectricDruid]

Do you use a stereo Input jack (with sleeve and ring)..??

If yes, is Input plug plugged when you take measurements..??

Good spot, Antonis.

[pinkjimiphoton]

changing the 220n cap to 100n is likely where you got the tonal change, you're wiping out about an octave + of low mid/bass frequencies that are needed to actually make the unit overdrive.
just a guess, never liked toob skreemers, so never built one.

welcome to the forum, btw!!

put the 220n back in and i bet the whole pedal will phatten back up.

[bluebunny]

changing the 220n cap to 100n is likely where you got the tonal change
. . .
put the 220n back in

If all you have is 100nF caps, then tack another in parallel - voilà: 200nF (close enough for rock'n'roll).

[aron]

Usually what I do is measure voltages at the IC to test whether it's getting power. Then I audio probe the input cap etc... and output.
But this sounds like a wiring error to me. This is a great circuit to start debugging with because we all understand the signal flow.